Problems installing Office Professional 2007 upgrade

Help! Problems installing Office Professional 2007 upgrade.

I bought the upgrade for my Office Professional 2007 version, and installed
it ith no problem on my computer. Unfortunately, this the hard drive crashed
Tuesday. So, rather than buy a new hard drive, I simply used a hard drive in
an extra CPU from my the office that was shut down last year. This computer
has office 2003 on it and was in a networked office. When I tried to install
the upgrade, I ran into a problem. This is what happened: I put in my
Office Professional 2007 upgrade disks, enter product key, is ok'd, and then
I get the following message: "Setup cannot find
office.en-us\1033\dwintl20.dll. Browse to a valid installation source." I
found some dwintl20.dll files on my hard drive, but when I click OK, it won't
accept any. So, it cancels the upgrade installation.

The only thing I could think of that would be a problem was that this
particular hard drive was in a computer at an office that was networked with
the original information being on the network. Of course, I did not reformat
the hard drive before installing.

Regardless, what can I do NOW? Should install my own older version of
Office that was on the crashed computer, then uninstall Office 2003, then try
installing the upgrade again?

Can anyone help?

Thank you.